Medusce of the Philippines and of Torres Straits. 



189 



ring-canal which is beneath an annular furrow or bend in the subumbrella 

 13 mm. inward from the bell-margin. On its inner side the ring-canal gives 

 rise to from 4 to 7, usually 5, centripetal canals between each successive pair 

 of radial-canals. These centripetal vessels anastomose with one another and 

 with the 16 radial-canals, and end blindly before leaching the stomach margin. 

 On its outer side the ring-canal gives off a network of vessels which ramify 

 through the lappets. In formalin the medusa is opaque milky white^with 

 irregularly clustered brown spots over the exumbrella. 



FIG. 5. Catostylus townsendi, from off Mount Putri, Borneo, September 30, 1901*. 



This medusa is closely related to Acromitus maculosus Light (1914, Phil- 

 ippine Journal of Science, vol. 9, No. 3, sec. D, p. 212, figs. 4-6), but it has no 

 filaments upon its mouth-arms. It is possible, however, that these were lost, 

 but this seems improbable among 6 well-preserved specimens. 



Moreover, in Catostylus townsendi the centripetal vessels anastomose with 

 the 16 radial-canals, whereas in Acromitus they join only with the 8 rhopalar 

 canals. It seems probable, therefore, that Catostylus townsendi is a distinct 

 species separate from Acromitus maculosus Light, and that Acromitus is a genus 

 derived from a mutation from Catostylus. 



